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Unformatted text preview: Module 08.Basic Aerodynamics 08.1. Physics of the Atmosphere. Question Number. 1. The ISA. Option A. assumes a standard day. Option B. is taken from the equator. Option C. is taken from 45 degrees latitude. Correct Answer is. is taken from 45 degrees latitude. Explanation. The properties of a standard day are related to sea level at latitude 45 degrees latitude. See the Forum for more details. Question Number. 2. At higher altitudes as altitude increases, pressure. Option A. decreases at constant rate. Option B. decreases exponentially. Option C. increases exponentially. Correct Answer is. decreases exponentially. Explanation. Pressure decreases  sure! But the rate of decrease reduces with altitude. At 18000 ft, half the pressure is lost already, and there is still another 40,000ft or so to go. Question Number. 3. When the pressure is half of that at sea level, what is the altitude?. Option A. 12,000 ft. Option B. 18,000 ft. Option C. 8,000 ft. Correct Answer is. 18,000 ft. Explanation. Just one of those facts you have to learn  but it is quoted in just about every text book on CAA reading list. Question Number. 4. If gauge pressure on a standard day at sea level is 25 PSI, the absolute pressure is. Option A. 39.7 PSI. Option B. 10.3 PSI. Option C. 43.8 PSI. Correct Answer is. 39.7 PSI. Explanation. Absolute pressure = gauge pressure plus atmospheric pressure. Atmospheric pressure at seallevel = 14.7 PSI. Question Number. 5. Pressure decreases. Option A. inversely proportional to temperature. Option B. proportionally with a decreases in temperature. Option C. Pressure and temperature are not related. Correct Answer is. proportionally with a decreases in temperature. Explanation. Temperature and volume are directly proportional  Charles' Law. Question Number. 6. As air gets colder, the service ceiling of an aircraft. Option A. reduces. Option B. increases. Option C. remains the same. Correct Answer is. increases. Explanation. As air gets colder it gets denser. Lift increases (remember the lift equation has density) and the engines produce more thrust  so it can climb higher. Question Number. 7. What is sea level pressure?. Option A. 1012.3 mb. Option B. 1013.2 mb. Option C. 1032.2 mb. Correct Answer is. 1013.2 mb. Explanation. Learn the ISA sea level quantities, in all units. Question Number. 8. How does IAS at the point of stall vary with height?. Option A. It decreases. Option B. It is practically constant. Option C. It increases. Correct Answer is. It is practically constant. Explanation. The stalling IAS at altitude is practically the same as it is at sea level. That's because IAS is not corrected for density. Question Number. 9. What is the lapse rate with regard to temperature?....
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 One '11
 DR.ALAN
 Aerodynamics, Correct Answer, Airfoil, Question Number.

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